With the development of communication technology, mobile communication system develops to a System Architecture Evaluation (SAE) system. FIG. 1 is a schematic diagram illustrating the structure of an existing SAE system. As illustrated in FIG. 1, the system includes an Evolved Universal terrestrial radio access network (E-UTRAN) 101 and a core network at least including a Mobility Management Entity (MME) 105, and a user plane entity (S-GW) 106. The E-UTRAN is used to connect a user equipment (UE) to the core network. The E-UTRAN 101 further includes more than one macro base station (eNB)s 102 and home base stations (HeNB) 103, optionally includes a home base station gateway (HeNB GW) 104. The MME 105 and the S-GW 106 can be integrated in a model to implement, or can be separated to implement independently.
Here, the eNB 102s are connected to each other via X2 interface, and are respectively connected to the MME 105 and the S-GW 106 via S1 interface, or are connected with the optional HeNB GW 104, and then the HeNB GW 104 is respectively connected with the MME 105 and S-GW 106 via S1 interface.
In an initial stage of establishment of the SAE system or in a process of operation of the SAE system, a lot of human and material resource is spent on configuration and optimization of a parameter of the SAE system, particularly on setting of a radio parameter, thus to guarantee good coverage and capacity of the SAE system, mobile robustness, load balancing when the user equipment moves, and access speed of the user equipment etc. At present, a method for self-optimization of the SAE system is provided to save the configuration of the human and the material during the operation of the SAE system. During a process of the self-optimization, the configuration of the eNB and the HeNB is carried out the process of the optimization according to current state of the SAE system. The eNB and the HeNB are generally referred to as “eNB” hereinafter, to instruct the method for the self-optimization of the SAE system.
FIG. 2 is a schematic diagram illustrating the rationale of existing self-optimization for a SAE system, as illustrated in FIG. 2, after the eNB powers up or accesses SAE, eNB can perform the process of self-optimization. The process includes a basic configuration for the eNB, and initialization for the configuration of the radio parameter. Here, the basic configuration for the eNB includes configuration of Internet Protocol (IP) address and detection operation, administration and management (OA&M); authentication between the eNB and the core network; if the eNB acts as a HeNB, the HeNB GW to which the HeNB belongs is further needed to be detected; downloading software and the operation parameter of the eNB and processing self-configuration. The initialization for the configuration of the radio parameter is that eNB needs to initial the configuration of the radio parameter according to environment of region where the eNB locates, since performance of each eNB of the SAE system can be impacted by the environment of the region where the eNB locates.
After the process of the self-configuration is finished, a lot of parameters configured by the eNB are not the optimization, for the better performance of the SAE system, the optimization or adjustment for the eNB configuration is needed, also referred to as self-optimization of mobile communication system. During the process of the optimization or adjustment for the eNB configuration, the eNB controlled by the OA&M in the background can perform the process. there can be a standardized interface between the OA&M and the eNB, the OA&M in the background sends the parameter to be optimized via the interface to the eNB (can be the eNB or HeNB), and then the eNB optimizes the parameter configured on itself, according to the parameter to be optimized. Certainly, the process can also be performed by the eNB itself, i.e. the eNB detects and acquires the performance to be optimized, optimizes and adjusts the corresponding parameter of the eNB itself. The processing of the optimization or adjustment for the eNB configuration includes: self-optimization of a neighbor cell list, self-optimization of coverage and capacity, self-optimization of mobile robustness, self-optimization of load balancing, and self-optimization of a random access channel parameter etc.
At present, the basic principle of self-optimization for mobile robustness in Release 10 is: radio link failure (RLF) or handover failure occurs on the UE, the UE indicates a network that the UE has available RLF report, when the UE is back to a connection mode, the network sends a message to UE to request the report, the RLF report sent by the UE includes the following information: a global cell identity (ECGI) of the cell lastly serving the UE, an ECGI of the cell where the UE attempts to re-establish, the ECGI of the cell where the process of a handover at the last time is triggered, a time interval from the triggering for the handover at the last time to the occurrence of connection failure, a reason of the connection failure, RLF or handover failure, radio measurement. A base station acquiring the RLF report from the UE forwards the acquired RLF report from the UE to the base station lastly serving the UE. The base station lastly serving the UE decides the reason of too early handover, too late handover, handover to an error cell or a coverage hole, if the reason is too early handover or handover to an error cell, the base station sends the information of too early handover or handover to an error cell to the base station where the too early handover is triggered or to the base station of the cell to which UE is handed over.
However, if the existing mechanism is used to detect RLF or handover failure between different RATs (Inter-RAT), efficiency is particular low. Moreover, a problem that the configuration of an RAT is not the optimization, may bring additional processing burden for another RAT. For example, for too late handover from LTE to 3G, if the UE has a re-establishment in 3G at the first time after failure, the UE needs to send the RLF report to the 3G network side, actually the problem is that the handover is not triggered in time in LTE, thus the additional burden is brought to 3G system. If the UE always reports after the UE returns to LTE, there is also a problem. For example for too early handover from 3G to LTE, if the UE always reports after the UE is return to LTE, the unnecessary burden is brought to LTE system, since the unreasonable 3G configuration brings the problem, but the UE needs to report back to LTE. Moreover, after the LTE system receives the RLF report, the LTE system needs to send the RLF report to the cell lastly serving the UE in 3G system, via S1/Iu interface, additional signal interaction is brought.